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I worked several hours on an avalanche of small optimizations. The
avalanche was caused by #1445 (a ticket which I created only
now, it is the idea of having multiple roles per user type, which I
started for #1400. I now basically revoked that idea and went
back to where I was before (every user type has one and only user
role), except that things have become more clear (or at least I hope
so).